I think that your tank is way too small to be packing cichlids in there. I think you've got too much going on as it is I could not suggest adding anything, especially not a jack Dempsey. Clown loaches grow longer than your tank is wide, so how would you suppose one would turn around? Honestly, once all the fish you have are grown, there would be no where for them to swim. I'm sure the fish are small now, but they dont stay that way. I bought my one severum at 2 inches and in a year it was 6 inches - easily increased overall size by 8 times.
I just don't think it's a stock list that is sustainable long term.